A method for recovering valuable metals from waste lithium-ion batteries

Abstract

The present invention discloses a method for recovering valuable metals from waste lithium-ion batteries. The method comprises the following steps: S1: discharging the waste lithium-ion batteries in a sulfate-containing discharge solution, then mixing with sulfate and / or sulfide and pyrolyzing and roasting, spraying the sulfate-containing solution during the pyrolysis and roasting process to recover battery black powder; S2: using a solvent to extract metal ions from the battery black powder, extracting and precipitating lithium to obtain lithium carbonate and nickel, cobalt and manganese sulfate. The method of the present invention uses a sulfate solution to discharge waste lithium-ion batteries, which can promote the sulfation of valuable metals in the waste lithium-ion batteries and improve the pyrolysis and roasting effect. The method of the present invention controls the pyrolysis and roasting temperature by spraying the sulfate-containing solution during the pyrolysis and roasting process, thereby avoiding excessively high pyrolysis and roasting temperatures that would otherwise result in the production of large amounts of metal alloys and impurities.

Description

Technical Field

[0001] The present invention belongs to the field of waste material recycling, and in particular relates to a method for recycling valuable metals from waste lithium-ion batteries. Background Art

[0002] Currently, the recovery of valuable metals from spent lithium-ion batteries mostly involves a wet recovery process involving reducing acid leaching to dissolve the metal ions. The metal ions are then recovered using precipitation, extraction, crystallization, and resynthesis. While this wet recovery route is mature and adaptable, it is associated with lengthy processes, low metal recovery rates, and high auxiliary material costs. In addition to dissolution methods for recovering valuable metals, the industry also uses pyrometallurgy to recover valuable metals. Pyrometallurgy involves placing spent battery materials into a high-temperature pyrolysis furnace under high temperatures, controlling the reaction within different temperature ranges. The heated waste lithium-ion battery cathode material undergoes a series of physical and chemical changes, and the valuable metal elements are then separated based on the properties of the resulting products. Pyrometallurgy is the simplest method for processing spent batteries, offering high throughput and a high degree of automation. However, pyrometallurgy is associated with difficulties in controlling the temperature of the pyrolysis furnace, significant safety risks, high levels of impurities and alloys in the resulting black powder, and difficulties in post-processing.

[0003] Currently, the most commonly used technology for recovering valuable metals is a combined pyrometallurgical and hydrometallurgical recovery process. CN106505270A provides a method for recovering valuable metals from waste lithium-ion battery positive electrode materials, including discharging with a salt solution; disassembling and separating the positive electrode sheets; crushing the positive electrode sheets to separate the positive electrode material and aluminum foil; mixing the positive electrode material with a calcining agent, ammonium sulfate and / or ammonium bisulfate, and calcining at low temperature; leaching the calcined material in water to separate the carbon and the leachate; adding a precipitant to the leachate and adjusting the pH using NH3-containing flue gas to precipitate other metals except Li, and performing solid-liquid separation; adjusting the pH of the filtrate using NH3-containing flue gas, adding ammonium carbonate or ammonium bicarbonate or bubbling CO2 gas to precipitate lithium and obtain a lithium carbonate product. This method requires manual disassembly to obtain the positive electrode sheets, resulting in a small amount of waste battery processing and high labor costs, making it unsuitable for large-scale production. The positive electrode material remaining in the subsequent water leaching residue is not effectively recycled, resulting in a waste of resources. CN113764758A provides a method for recycling waste lithium batteries by pyrolysis and temperature control. The method comprises the following steps: mixing the waste battery raw materials with a solid medium such as quartz sand, coal slag, or crushed stone, performing anaerobic pyrolysis, screening, crushing, and sorting to obtain battery powder; the pyrolysis temperature can be controlled between 350°C and 550°C. This method introduces difficult-to-treat impurities such as quartz stone, increasing the processing capacity of subsequent wet recovery. This method significantly increases the amount of waste residue to be treated, increasing processing costs and difficulty, and also suffers from a low recovery rate of valuable metals.

[0004] Therefore, there is an urgent need to develop a new method for recovering valuable metals from waste lithium-ion batteries to overcome the common problems that need to be solved in the field of battery recycling and processing, such as the long wet recovery process route, large amount of auxiliary materials, low metal recovery rate, low degree of automation in the battery pretreatment section, and difficulty in controlling the temperature of the pyrolysis furnace in the fire recovery pretreatment. Summary of the Invention

[0005] In order to overcome the problems existing in the above-mentioned prior art, one of the objects of the present invention is to provide a method for recovering valuable metals from waste lithium-ion batteries. The method has a high degree of automation, an easy-to-control process, a large recovery volume per batch, a small amount of waste residue and waste liquid generated, and a low cost of recycling auxiliary materials.

[0006] A second object of the present invention is to provide a method for recovering valuable metals from waste lithium-ion batteries for use in battery recycling.

[0007] In order to achieve the above object, the technical solution adopted by the present invention is:

[0008] A first aspect of the present invention provides a method for recovering valuable metals from waste lithium-ion batteries, comprising the following steps:

[0009] S1: discharging the waste lithium-ion battery in a discharge solution containing sulfate, then mixing with sulfate and / or sulfide and pyrolyzing and roasting, spraying the sulfate-containing solution during the pyrolysis and roasting process to recover battery black powder;

[0010] S2: Use solvent to extract metal ions in battery black powder, extract lithium precipitate to obtain lithium carbonate and nickel cobalt manganese sulfate.

[0011] In the present invention, waste lithium-ion batteries are first discharged through a sulfate-containing discharge solution, and then the waste lithium-ion batteries and sulfate are crushed and mixed before being sent to a pyrolysis furnace for pyrolysis and roasting. By spraying the sulfate-containing solution into the pyrolysis furnace, the heat released during the pyrolysis of the waste lithium-ion batteries can be removed through water evaporation and heat absorption, maintaining a relatively stable pyrolysis temperature in the pyrolysis furnace, preventing the pyrolysis furnace from significantly increasing in temperature during the pyrolysis process and becoming unable to control the temperature. This, in turn, reduces the generation of a large amount of alloy material from the Ni, Co, and Mn elements in the waste lithium-ion batteries due to excessively high temperatures in the pyrolysis furnace, which is detrimental to the subsequent treatment of battery black powder. Spraying the sulfate-containing solution in step S1 of the present invention can, on the one hand, remove heat from the pyrolysis furnace through water evaporation and the decomposition of the sulfate, preventing the temperature in the pyrolysis furnace from being too high, thereby reducing the content of alloy or metal elements and other impurities in the battery black powder. On the other hand, spraying sulfate solution can replenish sulfate in the thermal decomposition process of waste lithium-ion batteries, so that the nickel, cobalt, manganese and lithium in the waste lithium-ion batteries can be fully converted into nickel, cobalt and manganese lithium sulfate.

[0012] Preferably, the sulfate-containing discharge solution further comprises sodium chloride.

[0013] Preferably, the waste lithium-ion battery is at least one of a ternary lithium-ion battery containing nickel, cobalt and manganese, a lithium cobaltate lithium-ion battery, a lithium manganate lithium-ion battery, and a lithium nickelate lithium-ion battery.

[0014] Preferably, the sulfate is at least one of ammonium sulfate, ammonium bisulfate, sodium bisulfate, sodium sulfate, potassium bisulfate, potassium sulfate, Na2S2O3, and Na2S2O7; further preferably, the sulfate is ammonium sulfate or ammonium bisulfate; even further preferably, the sulfate is ammonium sulfate.

[0015] When the sulfate is ammonium sulfate, the thermal decomposition of ammonium sulfate to produce SO2 can make the waste lithium-ion battery thermodynamically unstable and generate the corresponding sulfate. The specific reaction formula is as follows:

[0016] (NH4)2SO4→NH3+(NH4)HSO4

[0017] 2(NH4)HSO4→2NH3+2SO2+2H2O+O2

[0018] 2LiNi x Co y Mn 1-x-y O2+2SO2→Li2SO4+2xNiSO4+2yCoSO4+2(1-xy)MnSO4

[0019] 2LiNi x Co y Mn 1-x-y O2+2(NH4)HSO4→Li2SO4+2xNiSO4+2yCoSO4+2(1-xy)MnSO4+2H2O+2NH3+O2

[0020] Ni and Co can be directly converted into corresponding sulfates under sulfate roasting conditions, while the process of Mn element being converted into sulfate under sulfate roasting conditions is as follows:

[0021] 4LiMn2O4+10(NH4)2SO4→2(NH4)2Mn2(SO4)3+4Li(NH4)SO4+4MnO2+12NH3+6H2O+O25MnO2+5(NH4)2SO4→(N H4)2Mn2(SO4)3+Mn3O4+(NH4)3H(SO4)2+5NH3+2H2O+2O2LiNixCoyMnzO2→MnO2→Mn2O3→MnSO4→Na2Mn(SO4)2

[0022] Preferably, the sulfide is at least one of CuS, MnS, NiS, Na2S, and sulfur S8.

[0023] Preferably, the concentration of the sulfate solution in step S1 is 100-750 g / L; further preferably, the concentration of the sulfate solution in step S1 is 300-500 g / L.

[0024] Preferably, the discharge time is 1 to 6 hours; further preferably, the discharge time is 2 to 4 hours.

[0025] Preferably, the step of mixing with sulfate and / or sulfide in step S1 is specifically: mixing the waste lithium ion batteries with sulfate and / or sulfide and crushing them to obtain a mixture of the waste lithium ion batteries and sulfate and / or sulfide.

[0026] Preferably, the temperature of the pulverizing step is 50-250°C; more preferably, the temperature of the pulverizing step is 60-200°C.

[0027] Preferably, the crushing time is 0.5 to 6 hours; more preferably, the crushing time is 1 to 6 hours.

[0028] Preferably, the step of extracting and precipitating lithium to obtain lithium carbonate and nickel, cobalt and manganese sulfate is specifically: extracting the leachate after battery black powder is leached with a solvent to obtain a nickel, cobalt and manganese sulfate solution and a lithium sulfate solution, then removing impurities from the lithium sulfate solution and concentrating it, and then precipitating lithium to obtain lithium carbonate and nickel, cobalt and manganese sulfate.

[0029] Preferably, in the extraction step, the extractant is at least one of a P507 extractant and a P204 extractant.

[0030] Preferably, the impurity removal step is specifically as follows: adding calcium oxide to the lithium sulfate solution, adjusting the pH to 8-9 and the temperature to 60-90° C., then adding carbonate and filtering. The carbonate added in this step is used to remove calcium impurities in the lithium sulfate solution.

[0031] Preferably, the molar ratio of the carbonate to calcium oxide is 1:1.

[0032] Preferably, the concentration step is specifically: concentrating the lithium sulfate solution to a lithium ion content of 8 to 15 g / L.

[0033] Preferably, the pH of the lithium precipitation step is 10.5 to 12.5.

[0034] Preferably, the temperature of the lithium precipitation step is 30-90°C; further preferably, the temperature of the lithium precipitation step is 40-80°C; even further preferably, the temperature of the lithium precipitation step is 60-80°C.

[0035] Preferably, the lithium precipitation step lasts for 0.5 to 3 hours; further preferably, the lithium precipitation step lasts for 1 to 3 hours.

[0036] Preferably, the sulfate-containing solution in step S1 is: a sulfate-containing solution obtained by passing the waste gas generated in the pyrolysis and roasting step into a mixture of the waste liquid generated in the lithium precipitation step and sulfuric acid; or, a sulfate-containing solution obtained by recovering the waste liquid generated in the discharge step. The mixture of the waste liquid generated in the lithium precipitation step and sulfuric acid can be used to absorb the ammonia-containing waste gas in the waste gas generated in the pyrolysis furnace. This step can realize the recycling of the lithium precipitation waste liquid and the recycling of sulfate. The NH3-containing waste gas discharged from the pyrolysis furnace is directly introduced into the waste liquid generated in the lithium precipitation step after adding sulfuric acid acidification, so as to recover the ammonia in the tail gas generated in the pyrolysis and roasting step to generate ammonium sulfate solution, and then the lithium precipitation waste liquid after absorbing the tail gas is sprayed into the pyrolysis furnace for recycling, thereby reducing the consumption of ammonium sulfate auxiliary material and reducing production costs. Alternatively, the ammonium sulfate solution can be crystallized and precipitated to recover ammonium sulfate, and then put into step S1 to be crushed and mixed with the waste lithium-ion batteries.

[0037] Preferably, the molar ratio of the amount of sulfuric acid to the amount of sulfate and / or sulfide in step S1 is (0.5-2.5):1; further preferably, the molar ratio of the amount of sulfuric acid to the amount of sulfate and / or sulfide in step S1 is (1-2.5):1; even further preferably, the molar ratio of the amount of sulfuric acid to the amount of sulfate and / or sulfide in step S1 is (1-2):1.

[0038] Preferably, the temperature of the waste liquid generated in the lithium precipitation step is 60-80°C.

[0039] Preferably, the spray flow rate of the sulfate-containing solution is 0.5 to 3.5 m 3 / h; further preferably, the spray flow rate of the sulfate-containing solution is 1 to 3m 3 / h.

[0040] Preferably, the mass ratio of sulfate in the sulfate and / or sulfide to waste lithium-ion batteries is (0.6-1.2):1.

[0041] Preferably, the pyrolysis and calcination temperature is 350-600°C; further preferably, the pyrolysis and calcination temperature is 350-500°C; even further preferably, the pyrolysis and calcination temperature is 400-500°C.

[0042] Preferably, the pyrolysis and calcination time is 30 to 150 minutes; more preferably, the pyrolysis and calcination time is 40 to 120 minutes.

[0043] Preferably, the pyrolysis calcination is carried out in the presence of an oxygen-containing gas.

[0044] Preferably, the oxygen-containing gas is air or oxygen.

[0045] Preferably, the step of recovering battery black powder is specifically: crushing and screening the pyrolysis and roasting products to obtain battery black powder.

[0046] Preferably, the crushing time is 30 to 150 minutes; more preferably, the crushing time is 40 to 120 minutes.

[0047] Preferably, copper-aluminum slag is obtained after the crushing and screening.

[0048] Preferably, in step S2, the leaching time is 50 to 200 minutes; further preferably, in step S2, the leaching time is 60 to 150 minutes.

[0049] Preferably, in step S2, the leaching temperature is 30-90°C; further preferably, in step S2, the leaching temperature is 40-80°C.

[0050] Preferably, the step of using a solvent to extract the metal ions in the battery black powder obtains a leachate and a leach residue.

[0051] Preferably, the solid-liquid ratio of the solvent to the battery black powder is 2 to 10 L / kg.

[0052] Preferably, the solvent is water.

[0053] Preferably, the leaching residue is transferred to a wet acid leaching reduction system for treatment.

[0054] The second aspect of the present invention is to provide the application of the above method for recovering valuable metals from waste lithium-ion batteries in battery recycling.

[0055] The present invention has the beneficial effects of using a sulfate solution to discharge waste lithium-ion batteries, allowing the sulfate to fully infiltrate and contact the positive electrode material in the waste lithium-ion batteries, thereby promoting the sulfation of valuable metals in the waste lithium-ion batteries and improving the pyrolysis and roasting effect. Furthermore, by spraying a sulfate-containing solution during the pyrolysis and roasting process, the method of the present invention can remove heat generated by the pyrolysis of the waste lithium-ion batteries through water evaporation and pyrolysis of the sulfate, thereby controlling the pyrolysis and roasting temperature and preventing excessively high pyrolysis and roasting temperatures from generating large amounts of metal alloys and impurities.

[0056] In addition, the method of the present invention realizes the recovery and treatment of the lithium precipitation waste liquid and the pyrolysis waste gas by mixing the waste liquid generated by lithium precipitation with sulfuric acid and then using the mixture to absorb the ammonia-containing waste gas generated in the pyrolysis and roasting process. At the same time, the recovered discharge solution and lithium precipitation waste liquid are sprayed in the pyrolysis and roasting process. On the one hand, the pyrolysis and roasting temperature can be reduced, and the pyrolysis and roasting furnace temperature can be precisely controlled. On the other hand, sulfate components can be supplemented for the pyrolysis of waste lithium-ion batteries, thereby improving the sulfation of valuable metals in the waste lithium-ion batteries, reducing the impurity content, and significantly reducing the amount of slag of battery black powder after water immersion, which can reduce the processing volume required for acid leaching reduction wet recovery, reduce the amount of auxiliary materials used in subsequent process treatment processes, and reduce process costs.

[0057] The method of the present invention directly discharges the entire waste lithium-ion battery material and then pyrolyzes and roasts it to recover valuable metals. This eliminates the need to separate the positive electrode material from the waste lithium-ion battery material. This method features a high degree of automation, reduced labor costs, a simple and easy-to-operate recovery process, and reduced processing costs. Furthermore, the discharge waste liquid, lithium precipitation waste liquid, and pyrolysis and roasting waste gas generated in this method can all be recycled, resulting in minimal waste residue and a simple post-processing process, further meeting the requirements of a green and environmentally friendly recycling process. During the discharge process, harmful organic matter, such as the electrolyte, from the waste lithium-ion battery that enters the sulfate solution can be thermally decomposed in the pyrolysis furnace, reducing the amount of electrolyte-containing discharge waste liquid to be processed.

[0058] The method of the present invention can achieve selective extraction of nickel and cobalt, reduce manganese sulfation, and further achieve selective extraction of valuable metals by adjusting the mass ratio of sulfate to waste lithium-ion batteries in combination with furnace temperature adjustment. BRIEF DESCRIPTION OF THE DRAWINGS

[0059] Figure 1 This is an SEM image of the battery black powder obtained by the method in Example 3.

[0060] Figure 2 This is the SEM image of the leached residue obtained by the method in Example 3.

[0061] Figure 3 Schematic diagram of the process of recovering valuable metals from waste lithium-ion batteries in Examples 1 to 4. DETAILED DESCRIPTION

[0062] The specific implementation of the present invention is further described in detail below with reference to the accompanying drawings and examples, but the implementation and protection of the present invention are not limited thereto. It should be noted that if there are any processes that are not particularly described in detail below, they can be implemented or understood by those skilled in the art with reference to the prior art. If the manufacturer of the reagents or instruments used is not indicated, they are deemed to be conventional products that can be purchased commercially.

[0063] The test method for the valuable metal content in the battery black powder in Examples 1 to 4 of the present invention and Comparative Examples 1 to 2 is as follows:

[0064] Weigh 5g of the sample and place it in a 100mL beaker. Add an appropriate amount of deionized water. First, use a magnetic rod wrapped in a ziplock bag to stir the battery black powder sample to adsorb the magnetic nickel, cobalt, manganese and iron elements. Then add 30mL of aqua regia composed of concentrated hydrochloric acid and concentrated nitric acid (the volume ratio of concentrated hydrochloric acid and concentrated nitric acid is 3:1) to dissolve the magnetic adsorbent and the remaining battery black powder. After dilution, use an ICP inductively coupled plasma mass spectrometer to test the concentration of each metal ion.

[0065] The method for testing the concentration of main metal ions in the leachates in Examples 1 to 4 of the present invention and Comparative Examples 1 to 2 is as follows: after dilution, the concentration of each metal ion is tested using an ICP inductively coupled plasma mass spectrometer.

[0066] Example 1:

[0067] The method for recovering valuable metals from waste lithium-ion batteries in this example comprises the following steps:

[0068] (1) One ton of waste ternary lithium-ion batteries is placed in a 100 g / L aqueous solution of ammonium sulfate for discharge treatment. The batteries are discharged in the ammonium sulfate solution for 4 h. The discharged waste ternary lithium-ion batteries are taken out, 1000 kg of ammonium sulfate is added to mix, and the batteries are mixed and crushed in a crusher for 0.5 h to obtain solid battery materials. The liquid discharge solution is then recovered.

[0069] (2) The crushed and mixed battery materials in step (1) are sent to a pyrolysis furnace for pyrolysis and roasting in an air atmosphere at 350°C for 120 minutes. During the roasting process, the recovered liquid discharge solution is sprayed into the pyrolysis furnace at a spray flow rate of 0.5m 3 / h, collecting ammonia-containing waste gas generated by roasting;

[0070] (3) The material after pyrolysis and roasting in step (2) was crushed in a crusher for 40 minutes and sieved to obtain battery black powder and copper-aluminum slag; a small amount of battery black powder was taken and the valuable metal content in the battery black powder was measured. The measurement results are shown in Table 1.

[0071] (4) The battery black powder obtained in step (3) was mixed with water at a solid-liquid ratio of 1kg:10L, stirred at 30°C for 60min, and then the solid and liquid were separated to obtain leaching residue and leachate. The obtained 320.5kg leaching residue was transferred to a wet acid leaching reduction system for treatment. A small amount of leachate was taken and the concentration of the main ions in the leachate was measured. The results are shown in Table 2. The leaching rate of the main ions in the leachate was estimated based on the theoretical content composition of the positive electrode material of the waste battery (accounting for 40% of the total battery mass). The estimated leaching rate of the main ions in the leachate is shown in Table 3. In this embodiment, the main ion concentration and ion leaching rate in the leachate are: Li + The concentration is 3.56g / L, and the leaching rate is 95%; Ni 2+ The concentration is 10.35g / L, the leaching rate is 72%; Co 2+ The concentration is 4.06g / L, the leaching rate is 70%; Mn 2+ The concentration is 2.61 g / L and the leaching rate is 30%;

[0072] (5) first extracting the leachate with a P204 extractant to obtain a manganese sulfate solution, and then extracting the leachate after manganese removal with a P507 extractant to obtain a nickel cobalt sulfate solution and a lithium sulfate solution, respectively;

[0073] (6) Add 6.5 kg of calcium oxide to the lithium sulfate solution to adjust the pH to 8 and the solution temperature to 60°C; then add 12.3 kg of sodium carbonate to remove calcium impurities in the solution;

[0074] (7) The lithium sulfate solution after impurity removal is evaporated and concentrated to Li + The concentration of the reaction mixture is 10 g / L, 194.4 kg of sodium carbonate is added to precipitate lithium at 60° C. to obtain lithium carbonate; and the waste liquid from the precipitation of lithium is recovered;

[0075] The ammonia-containing waste gas generated by the pyrolysis furnace in step (2) is passed into the lithium precipitation waste liquid, and 525L concentrated sulfuric acid is added to the lithium precipitation waste liquid to absorb the ammonia-containing waste gas generated by the pyrolysis furnace, and then the lithium precipitation waste liquid is heated to 2m 3 / h flow rate spraying into the pyrolysis furnace to increase the roasting circulation volume of ammonium sulfate in the pyrolysis furnace.

[0076] In this embodiment, the waste gas and waste liquid generated in all steps can be effectively recycled and reused. For example, the ammonia-containing waste gas generated by the pyrolysis in the pyrolysis furnace in step (2) can be passed into the lithium precipitation waste liquid in step (8), and 525L of concentrated sulfuric acid is added to the lithium precipitation waste liquid to fully absorb the ammonia-containing waste gas. The lithium precipitation waste liquid that has absorbed the ammonia-containing waste gas can be put back into the pyrolysis furnace (at a rate of 2m 3 / h flow rate spraying into the pyrolysis furnace) to promote the roasting circulation of ammonium sulfate in the pyrolysis furnace in the previous step and improve the metal recovery efficiency.

[0077] Example 2:

[0078] The method for recovering valuable metals from waste lithium-ion batteries in this example comprises the following steps:

[0079] (1) 1 ton of waste ternary lithium-ion batteries is placed in a 300 g / L aqueous solution of ammonium sulfate for discharge treatment, discharged in the ammonium sulfate solution for 3 h, the discharged waste ternary lithium-ion batteries are taken out, 1000 kg of ammonium sulfate is added for mixing, and the mixture is mixed and crushed in a crusher for 2 h to obtain solid battery materials; and then the liquid discharge solution is recovered;

[0080] (2) The crushed and mixed battery materials in step (1) are sent to a pyrolysis furnace for pyrolysis and roasting in an air atmosphere at 400°C for 100 minutes. During the roasting process, the recovered liquid discharge solution is sprayed into the pyrolysis furnace at a spray flow rate of 2m 3 / h, collecting ammonia-containing waste gas generated by roasting;

[0081] (3) The material after pyrolysis and roasting in step (2) was crushed in a crusher for 100 minutes and sieved to obtain battery black powder and copper-aluminum slag; a small amount of battery black powder was taken and the valuable metal content in the battery black powder was measured. The measurement results are shown in Table 1.

[0082] (4) The battery black powder obtained in step (3) was mixed with water at a solid-liquid ratio of 1 kg: 10 L, stirred at 50 ° C for 120 minutes, and then the solid and liquid were separated to obtain leaching residue and leachate. The obtained 294.2 kg leaching residue was transferred to the wet acid leaching reduction system for treatment. A small amount of leachate was taken and the main ion concentration in the leachate was measured. The results are shown in Table 2. The main ion leaching rate in the leachate was estimated based on the theoretical content composition of the waste battery positive electrode material (accounting for 40% of the total battery mass). The main estimated ion leaching rate in the leachate is shown in Table 3. In this embodiment, the main ion concentration and ion leaching rate in the leachate are: Li + The concentration is 3.62g / L, and the leaching rate is 98%; Ni 2+ The concentration is 12.22 g / L, and the leaching rate is 85%; Co 2+ The concentration is 4.76g / L, the leaching rate is 82%; Mn 2+ The concentration is 4.35 g / L and the leaching rate is 50%;

[0083] (5) extracting the leachate with a P507 extractant to obtain a nickel-cobalt-manganese sulfate solution and a lithium sulfate solution;

[0084] (6) Add 11.5 kg of calcium oxide to the lithium sulfate solution to adjust the pH to 8.5 and the solution temperature to 70°C; then add 21.8 kg of sodium carbonate to remove calcium impurities in the solution;

[0085] (7) The lithium sulfate solution after impurity removal is evaporated and concentrated to Li + The concentration of the precipitate is 12 g / L, 205.8 kg of sodium carbonate is added to precipitate lithium at 70° C. to obtain lithium carbonate, and the waste liquid of the precipitated lithium is recovered;

[0086] The ammonia-containing waste gas generated by the pyrolysis furnace in step (2) is passed into the lithium precipitation waste liquid, and 525L concentrated sulfuric acid is added to the lithium precipitation waste liquid to absorb the ammonia-containing waste gas generated by the pyrolysis furnace, and then the lithium precipitation waste liquid is heated to 3m 3 / h flow rate spraying into the pyrolysis furnace to increase the roasting circulation volume of ammonium sulfate in the pyrolysis furnace.

[0087] In this embodiment, the waste gas and waste liquid generated in all steps can be effectively recycled and reused. For example, the ammonia-containing waste gas generated by the pyrolysis in the pyrolysis furnace in step (2) can be passed into the lithium precipitation waste liquid in step (8), and 525L of concentrated sulfuric acid is added to the lithium precipitation waste liquid to fully absorb the ammonia-containing waste gas. The lithium precipitation waste liquid that has absorbed the ammonia-containing waste gas can be put back into the pyrolysis furnace (at a rate of 3m 3 / h flow rate spraying into the pyrolysis furnace) to promote the roasting circulation of ammonium sulfate in the pyrolysis furnace in the previous step and improve the metal recovery efficiency.

[0088] Example 3:

[0089] The method for recovering valuable metals from waste lithium-ion batteries in this example comprises the following steps:

[0090] (1) 1 ton of waste ternary lithium-ion batteries is placed in a 500 g / L aqueous solution of ammonium sulfate for discharge treatment, discharged in the ammonium sulfate solution for 2 h, the discharged waste ternary lithium-ion batteries are taken out, 1000 kg of ammonium sulfate is added for mixing, and the mixture is mixed and crushed in a crusher for 6 h to obtain a solid battery material; and then the liquid discharge solution is recovered;

[0091] (2) The crushed and mixed battery materials in step (1) are sent to a pyrolysis furnace for pyrolysis and roasting in an air atmosphere at 500°C for 80 minutes. During the roasting process, the recovered liquid discharge solution is sprayed into the pyrolysis furnace at a spray flow rate of 3.5m 3 / h, collecting ammonia-containing waste gas generated by roasting;

[0092] (3) The material after pyrolysis and roasting in step (2) was crushed in a crusher for 40 minutes and sieved to obtain battery black powder and copper-aluminum slag; a small amount of battery black powder was taken and the valuable metal content in the battery black powder was measured. The measurement results are shown in Table 1.

[0093] (4) The obtained battery black powder was mixed with water at a solid-liquid ratio of 1kg:10L, stirred at 90°C for 150min, and then the solid and liquid were separated to obtain leaching residue and leachate. The obtained 182.3kg leaching residue was transferred to a wet acid leaching reduction system for treatment. A small amount of leachate was taken to measure the concentration of the main ions in the leachate. The measurement results are shown in Table 2. The main ion leaching rate in the leachate was estimated based on the theoretical content composition of the positive electrode material of the waste battery (accounting for 40% of the total battery mass). The main estimated ion leaching rate in the leachate is shown in Table 3. Among them, in this embodiment, the main ion concentration and ion leaching rate in the leachate are: Li + The concentration is 3.64g / L, and the leaching rate is 98%; Ni 2+ The concentration is 12.94 g / L, and the leaching rate is 90%; Co 2+ The concentration is 5.30g / L, the leaching rate is 91%; Mn 2+ The concentration is 6.96 g / L and the leaching rate is 85%;

[0094] (5) extracting the leachate with a P507 extractant to obtain a nickel-cobalt-manganese sulfate solution and a lithium sulfate solution;

[0095] (6) Add 16.25 kg of calcium oxide to the lithium sulfate solution to adjust the pH to 9 and the solution temperature to 60°C; then add 30.75 kg of sodium carbonate to remove calcium impurities in the solution;

[0096] (7) The lithium sulfate solution after impurity removal is evaporated and concentrated to Li + The concentration of the reaction mixture is 15 g / L, 208.5 kg of sodium carbonate is added to precipitate lithium at 80° C. to obtain lithium carbonate, and the waste liquid of lithium precipitation is recovered;

[0097] The ammonia-containing waste gas generated by the pyrolysis furnace in step (2) is passed into the lithium precipitation waste liquid, and 626L concentrated sulfuric acid is added to the lithium precipitation waste liquid to absorb the ammonia-containing waste gas generated by the pyrolysis furnace, and then the lithium precipitation waste liquid is heated to 3.5m 3 / h flow rate spraying into the pyrolysis furnace to increase the roasting circulation volume of ammonium sulfate in the pyrolysis furnace.

[0098] In this embodiment, the waste gas and waste liquid generated in all steps can be effectively recycled and reused. For example, the ammonia-containing waste gas generated by the pyrolysis in the pyrolysis furnace in step (2) can be passed into the lithium precipitation waste liquid in step (8), and concentrated sulfuric acid is added to the lithium precipitation waste liquid to fully absorb the ammonia-containing waste gas. The lithium precipitation waste liquid that has absorbed the ammonia-containing waste gas can be re-introduced into the pyrolysis furnace (at a rate of 3.5m 3 / h flow rate spraying into the pyrolysis furnace) to promote the roasting circulation of ammonium sulfate in the pyrolysis furnace in the previous step and improve the metal recovery efficiency.

[0099] The SEM images of the battery black powder obtained in step (3) and the leached residue obtained in step (4) were tested respectively, wherein the SEM image of the battery black powder is as follows: Figure 1 As shown in the SEM image of the leached residue Figure 2 As shown, by comparison Figure 1 and Figure 2 It can be seen that there are a large number of cavities on the leached residue where metal ions are dissolved.

[0100] Example 4:

[0101] The method for recovering valuable metals from waste lithium-ion batteries in this example comprises the following steps:

[0102] (1) 1 ton of waste ternary lithium-ion batteries was placed in a 750 g / L aqueous solution of ammonium sulfate for discharge treatment, discharged in the ammonium sulfate solution for 2 h, the discharged waste ternary lithium-ion batteries were taken out, 1200 kg of ammonium sulfate was added for mixing, and the mixture was crushed in a crusher for 6 h to obtain a solid battery material; and then the liquid discharge solution was recovered;

[0103] (2) The crushed and mixed battery materials in step (1) are sent to a pyrolysis furnace for pyrolysis and roasting in an air atmosphere at 600°C for 60 minutes. During the roasting process, the recovered liquid discharge solution is sprayed into the pyrolysis furnace at a spray flow rate of 3.5m 3 / h, collecting ammonia-containing waste gas generated by roasting;

[0104] (3) The material after pyrolysis and roasting in step (2) was crushed in a crusher for 40 minutes and sieved to obtain battery black powder and copper-aluminum slag; a small amount of battery black powder was taken and the valuable metal content in the battery black powder was measured. The measurement results are shown in Table 1.

[0105] (4) The battery black powder in step (3) was mixed with water at a solid-liquid ratio of 1kg:10L, stirred at 90°C for 150min, and then the solid and liquid were separated to obtain leaching residue and leachate. The obtained 235.3kg leaching residue was transferred to a wet acid leaching reduction system for treatment. A small amount of leachate was taken and the concentration of the main ions in the leachate was measured. The results are shown in Table 2. The main ion leaching rate in the leachate was estimated based on the theoretical content composition of the positive electrode material of the waste battery (accounting for 40% of the total battery mass). The main estimated ion leaching rate in the leachate is shown in Table 3. In this embodiment, the main ion concentration and ion leaching rate in the leachate are: Li + The concentration is 3.45g / L, and the leaching rate is 95%; Ni 2+ The concentration is 13.35g / L, the leaching rate is 80%; Co 2+ The concentration is 5.30g / L, the leaching rate is 73%; Mn 2+ The concentration is 6.84 g / L and the leaching rate is 70%;

[0106] (5) extracting the leachate with a P507 extractant to obtain a nickel-cobalt-manganese sulfate solution and a lithium sulfate solution;

[0107] (6) Add 16.25 kg of calcium oxide to the lithium sulfate solution to adjust the pH to 9 and the solution temperature to 60°C; then add 30.75 kg of sodium carbonate to remove calcium impurities in the solution;

[0108] (7) The lithium sulfate solution after impurity removal is evaporated and concentrated to Li + The concentration of the precipitate is 15 g / L, 208.5 kg of sodium carbonate is added and lithium is precipitated at 80°C to obtain lithium carbonate;

[0109] The ammonia-containing waste gas generated by the pyrolysis furnace in step (2) is passed into the lithium precipitation waste liquid, and 626L concentrated sulfuric acid is added to the lithium precipitation waste liquid to absorb the ammonia-containing waste gas generated by the pyrolysis furnace, and then the lithium precipitation waste liquid is heated to 3.5m 3 / h flow rate spraying into the pyrolysis furnace to increase the roasting circulation volume of ammonium sulfate in the pyrolysis furnace.

[0110] In this embodiment, the waste gas and waste liquid generated in all steps can be effectively recycled and reused. For example, the ammonia-containing waste gas generated by the pyrolysis in the pyrolysis furnace in step (2) can be passed into the lithium precipitation waste liquid in step (8), and concentrated sulfuric acid is added to the lithium precipitation waste liquid to fully absorb the ammonia-containing waste gas. The lithium precipitation waste liquid that has absorbed the ammonia-containing waste gas can be re-introduced into the pyrolysis furnace (at a rate of 3.5m 3 / h flow rate spraying into the pyrolysis furnace) to promote the roasting circulation of ammonium sulfate in the pyrolysis furnace in the previous step and improve the metal recovery efficiency.

[0111] The schematic flow diagram of the method for recovering valuable metals from waste lithium-ion batteries in Examples 1 to 4 is as follows: Figure 3 shown.

[0112] Comparative Example 1:

[0113] The method for recovering valuable metals from waste lithium-ion batteries in this example comprises the following steps:

[0114] (1) 1 ton of waste ternary lithium-ion batteries was placed in a 100 g / L sodium chloride solution for discharge treatment, and the discharged batteries were discharged in the salt water for 4 h. The discharged waste ternary lithium-ion batteries were taken out and mixed and crushed in a crusher for 0.5 h to obtain battery materials;

[0115] (2) The crushed and mixed battery materials in step (1) are fed into a pyrolysis furnace for pyrolysis in an air atmosphere for 120 minutes. Since there are no corresponding temperature control measures during the pyrolysis process, the furnace temperature rises to above 750°C.

[0116] (3) The material after pyrolysis in step (2) was crushed in a crusher for 40 minutes, and sieved to obtain battery black powder and copper-aluminum slag; the valuable metal content in the battery black powder was measured, and the measurement results were recorded in Table 1.

[0117] (4) The battery black powder obtained in step (3) was mixed with water at a solid-liquid ratio of 1 kg: 10 L, stirred at 30 ° C for 60 minutes, and then the solid and liquid were separated to obtain leaching residue and leachate. The obtained 786.5 kg leaching residue was transferred to the wet acid leaching reduction system for treatment. The main ion concentration in the leachate was measured and recorded in the following Table 2. Then, the main ion leaching rate in the leachate was estimated based on the theoretical content composition of the waste battery positive electrode material (accounting for 40% of the total battery mass). The main ion leaching rate data in the leachate are recorded in the following Table 3. The main ion concentration and ion leaching rate in the leachate are: Li + The concentration is 0.18g / L, the leaching rate is 4.8%; Ni 2+ The concentration is 0.33g / L, the leaching rate is 2.3%; Co 2+ The concentration is 0.05g / L, the leaching rate is 0.8%; Mn 2+ The concentration is 0.01g / L and the leaching rate is 0.2%.

[0118] Comparative Example 2:

[0119] The method for recovering valuable metals from waste lithium-ion batteries in this example comprises the following steps:

[0120] (1) 1 ton of waste ternary lithium-ion batteries were placed in a 100 g / L aqueous solution of ammonium sulfate for discharge treatment, discharged in the ammonium sulfate solution for 4 h, and the discharged waste ternary lithium-ion batteries were mixed with 1000 kg of ammonium sulfate and crushed in a crusher for 0.5 h;

[0121] (2) The crushed and mixed battery materials in step (1) are fed into a pyrolysis furnace for pyrolysis and roasting in an air atmosphere at 500°C for 120 minutes; the temperature of the pyrolysis furnace will reach 700°C without spraying the discharge ammonium sulfate solution for temperature control.

[0122] (3) The pyrolysis and roasting material in step (2) was crushed in a crusher for 60 minutes, and sieved to obtain battery black powder and copper-aluminum slag; the valuable metal content in the battery black powder was measured, and the measurement results were recorded in Table 1.

[0123] (4) The obtained battery black powder was mixed with water at a solid-liquid ratio of 1 kg: 10 L, stirred at 30 ° C for 60 minutes, and then the solid and liquid were separated to obtain leaching residue and leachate. The obtained 225.6 kg leaching residue was transferred to the wet acid leaching reduction system for treatment. The main ion concentration in the leachate was measured and recorded in the following Table 2. Then, the main ion leaching rate in the leachate was estimated based on the theoretical content composition of the waste battery positive electrode material (accounting for 40% of the total battery mass). The main ion leaching rate data in the leachate are recorded in the following Table 3. The main ion concentration and ion leaching rate in the leachate are: Li + The concentration is 3.37g / L, and the leaching rate is 90%; Ni 2+ The concentration is 10.11 g / L, the leaching rate is 71%; Co 2+ The concentration is 3.86g / L, the leaching rate is 68%; Mn 2+ The concentration is 5.39 g / L and the leaching rate is 62%;

[0124] (5) extracting the leachate with a P507 extractant to obtain a nickel-cobalt-manganese sulfate solution and a lithium sulfate solution;

[0125] (6) Add 5.9 kg of calcium oxide to the lithium sulfate solution to adjust the pH to 8 and the solution temperature to 60°C; then add 11.8 kg of sodium carbonate to remove calcium impurities in the solution.

[0126] Table 1 Valuable metal content in battery black powder in Examples 1 to 4 and Comparative Examples 1 to 2 (mass fraction %)

[0127]

[0128] As shown in Table 1 above, compared with Comparative Example 1, the battery black powder obtained by the methods of Examples 1-4 significantly increased the content of Ni, Co, and Mn ions, while significantly decreased the content of Al, Cu, and Fe ions. This indicates that discharging the spent ternary lithium-ion batteries in an ammonium sulfate solution allows the sulfate to fully infiltrate the spent ternary lithium-ion battery materials. Simultaneously, spraying the sulfate solution in the pyrolysis furnace to control the pyrolysis furnace temperature allows for the selective sulfation of the nickel, cobalt, and manganese elements in the spent ternary lithium-ion batteries, resulting in the selective leaching of Ni, Co, and Mn ions. Furthermore, compared with Comparative Examples 1-2, the methods of Examples 1-4, by spraying the sulfate solution in the pyrolysis furnace, can control the pyrolysis furnace temperature, thereby reducing the content of elemental Ni, Co, and Mn in the battery black powder and avoiding the formation of excessive alloying material of Ni, Co, and Mn elements in the spent ternary lithium-ion battery materials due to excessively high pyrolysis furnace temperatures. Compared with Examples 1 to 3, Example 4 adopts a pyrolysis roasting temperature of 600°C. At this temperature, part of the positive electrode material produces part of the alloy element due to the action of the graphite in the battery. Therefore, the content of nickel, cobalt and manganese elements in Example 4 is significantly higher than that in Examples 1 to 3, further indicating that the use of a calcination temperature of 350 to 500°C can reduce the content of nickel, cobalt and manganese elements and alloys in the battery black powder.

[0129] Table 2 Main ion concentrations in the leachate of Examples 1 to 4 and Comparative Examples 1 to 2

[0130] element Li(g / L) Ni(g / L) Co(g / L) Mn (g / L) Example 1 3.56 10.35 4.06 2.61 Example 2 3.62 12.22 4.76 4.35 Example 3 3.64 12.94 5.30 6.96 Example 4 3.45 13.35 5.30 6.84 Comparative Example 1 0.18 0.33 0.05 0.01 Comparative Example 2 3.37 10.11 3.86 5.39

[0131] As shown in Table 2 above, compared with Comparative Example 1, the methods of Examples 1-4 significantly improve the sulfation of Li, Ni, Co, and Mn elements and the recovery rate of Li, Ni, Co, and Mn by discharging the spent ternary lithium-ion batteries in an ammonium sulfate solution, allowing the sulfate to fully infiltrate the spent ternary lithium-ion battery materials. Furthermore, spraying the sulfate solution into the pyrolysis furnace to control the pyrolysis furnace temperature can significantly improve the sulfation of Li, Ni, Co, and Mn elements, thereby increasing the recovery rate of Li, Ni, Co, and Mn. Compared with Comparative Example 2, the methods of Examples 1-4 further improve the sulfation of Li, Ni, Co, and Mn elements by spraying the sulfate solution into the pyrolysis furnace to control the pyrolysis furnace temperature.

[0132] Table 3: Ion leaching rate and quality of leached residue in leachate of Examples 1 to 4 and Comparative Examples 1 to 2

[0133]

[0134] As shown in Table 3 above, compared with Comparative Example 1, the methods of Examples 1-4 significantly improve the leaching rate of Li, Ni, Co, and Mn ions, improve the recovery rate of Li, Ni, Co, and Mn ions, and significantly reduce the content of leached residue, reducing the amount of leached residue to be processed and the cost of leached residue processing. Compared with Comparative Example 2, the methods of Examples 1-4 further improve the leaching rate of Li, Ni, Co, and Mn ions by spraying the pyrolysis furnace with a sulfate solution to control the pyrolysis furnace temperature.

[0135] As shown in Tables 2-3 above, compared with Examples 1-2 and Example 4, Example 3, by spraying ammonium sulfate solution, controlled the pyrolysis furnace temperature at 500°C and controlled the mass ratio of sulfate to waste ternary lithium-ion battery material at 1:1, further improving the selective sulfate conversion of nickel, cobalt, and manganese. Compared with Examples 2-4, Example 1, by spraying ammonium sulfate solution, controlled the pyrolysis furnace temperature at 350°C and controlled the mass ratio of sulfate to waste ternary lithium-ion battery material at 1:1, reducing the sulfate conversion of Mn and primarily selectively leaching nickel and cobalt ions.

[0136] While the embodiments of the present invention have been described in detail above, the present invention is not limited to the embodiments described above. Various modifications may be made within the scope of knowledge possessed by a person skilled in the art without departing from the spirit of the present invention. Furthermore, the embodiments of the present invention and the features thereof may be combined with one another unless there is a conflict.

Claims

1. A method for recovering valuable metals from waste lithium-ion batteries, characterized in that: The following steps are involved: S1: discharging the waste lithium-ion battery in a discharge solution containing sulfate, then mixing with sulfate and / or sulfide and pyrolyzing and roasting, spraying the sulfate-containing solution during the pyrolysis and roasting process to recover battery black powder; S2: Use solvent to extract metal ions in battery black powder, extract lithium to obtain lithium carbonate and nickel cobalt manganese sulfate; The solvent is water; The solid-liquid ratio of the solvent to the battery black powder is 2 to 10 L / kg; The pyrolysis and calcination temperature is 350-600°C.

2. The method for recovering valuable metals from waste lithium-ion batteries according to claim 1, wherein: The steps of extracting and precipitating lithium to obtain lithium carbonate and nickel-cobalt-manganese sulfate are specifically as follows: extracting the leachate after battery black powder is leached with a solvent to obtain a nickel-cobalt-manganese sulfate solution and a lithium sulfate solution; then removing impurities from the lithium sulfate solution and concentrating it; and then precipitating lithium to obtain lithium carbonate and nickel-cobalt-manganese sulfate.

3. The method for recovering valuable metals from waste lithium-ion batteries according to claim 2, wherein: The impurity removal step is specifically as follows: adding calcium oxide to the lithium sulfate solution, adjusting the pH to 8-9 and the temperature to 60-90° C., then adding carbonate and filtering.

4. The method for recovering valuable metals from waste lithium-ion batteries according to claim 3, wherein: The molar ratio of the carbonate to calcium oxide is 1:

1.

5. The method for recovering valuable metals from waste lithium-ion batteries according to claim 1, wherein: The sulfate-containing solution in step S1 is obtained by passing the waste gas generated in the pyrolysis and roasting step into a mixture of the waste liquid generated in the lithium precipitation step and sulfuric acid; or by recovering the waste liquid generated in the discharge step.

6. The method for recovering valuable metals from waste lithium-ion batteries according to claim 5, wherein: The molar ratio of the amount of sulfuric acid to the amount of sulfate and / or sulfide in step S1 is (0.5-2.5):

1.

7. The method for recovering valuable metals from waste lithium-ion batteries according to claim 1 or 5, characterized in that: The spray flow rate of the sulfate-containing solution is 0.5~3.5m3 / h.

8. The method for recovering valuable metals from waste lithium-ion batteries according to claim 1, wherein: The mass ratio of sulfate ions in the sulfate and / or sulfide to waste lithium-ion batteries is (0.6-1.2):1.

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